Treatment for people with inhibitors

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Treatment for people with inhibitors

It can be difficult to treat a person with hemophilia who has inhibitors to the clotting factor. Inhibitors are produced by the body's natural defense system (immune system). The body thinks that the replacement clotting factors don't belong in the body, so it creates antibodies (inhibitors) to get rid of them. Some people produce few inhibitors; others produce many. Managing hemophilia in people who develop inhibitors depends on the amount of inhibitors produced.

If your body produces antibodies (inhibitors) that react with clotting factors, you can be treated with:

• Factor bypassing agents. These clotting factors are used to skip the part of the clotting process that requires either clotting factor VIII or IX. This treatment is unpredictable, and it is hard to determine the correct dose. It is also very expensive. This treatment also slightly increases your risk of having a heart attack or developing blood clots.
• A regimen that allows the body to get used to the clotting factor so that it won't produce as many or any inhibitors. This is done by giving large amounts of clotting factors daily over an extended period of time (1 to 3 years). During the first part of the treatment, you will get a factor bypassing agent along with the regular clotting factors to make sure that any injury will heal. Once the body starts getting used to the clotting factor, the bypassing agent is no longer needed. This is an expensive and lengthy method.
• Medication suppression of the immune system so it won't create any inhibitors or to make the inhibitors nonfunctional. This is a complicated treatment that requires special equipment.

If your body produces few inhibitors in reaction to clotting factors, you may use the treatments above. In addition, you may be treated with:

• Large doses of the clotting factor, which can overwhelm the inhibitors.
• Factors taken from pig plasma (porcine factors). People with a lot of inhibitors who do not respond to human clotting factors often respond well to porcine factors.
• A new clotting factor product (NovoSeven) that is produced in a lab. Since it is man-made and does not come from human blood products, there are no risks of getting viral infections when it is injected.

If your body produces many inhibitors, you may be treated by pumping your blood through a machine that removes or neutralizes the inhibitors (plasmapheresis) to reduce or neutralize the inhibitors in the body. This process only works temporarily and is used before a surgery or after a major injury. It is an expensive, lengthy, and complicated method.

Credits

Last updated:	August 20, 2007
Author:	Robin Parks, MS
Reviewed By:	Anne C. Poinier, MD - Internal Medicine, Brian Leber, MDCM, FRCPC - Hematology
Editors:	Kathleen M. Ariss, MS, Pat Truman